Multigene cancer tests giving doctors new hope

By
Amy Corderoy

RARE but treatable genetic mutations are being found in most cancer patients in a cutting-edge program at Royal Prince Alfred Hospital.

RARE but treatable genetic mutations are being found in most cancer patients in a cutting-edge program at Royal Prince Alfred Hospital.

Doctors are testing patients with melanoma, lung and colorectal cancers for a huge range of possible genetic mutations, opening the door to new, life-extending treatments.

Using new ''multigene'' tests, up to 80 per cent of melanoma patients treated at the hospital have been found with potentially treatable tumour mutations, compared to about 30 per cent discovered through standard single-gene tests.

But the growth in the discovery of treatable genetic mutations - errors in genes that can cause cells to grow out of control, becoming cancerous - is forcing an overhaul of the whole system of approving and funding new tests and treatments.

Sandra O'Toole, the head of molecular diagnostic oncology at the hospital, said doctors were able to direct patients into drug trials, or treat them with existing drugs that had previously been used in other cancers, on the basis of the newly found mutations.

''When you look at the patient samples we are finding things that have never been found before, and it's not going to save patients at this stage but it could extend their life,'' she said.

In early stages of the most common lung cancer, more than 50 per cent of patients have potentially treatable mutations, according to research she presented at the Royal College of Pathologists of Australasia's Pathology Update conference at the weekend.

''If we can find these treatable mutations in early cancer we can have real hope.''

Professor O'Toole said without big changes to the way cancer mutation tests were approved and funded, patients might not be able to access the multigene tests.

The federal system was arranged so that a drug company usually made an application for a specific drug and test.

But the small size of tissue samples meant doing one test at a time was impractical, as well as costly, she said. ''If you can do all the mutations at once you can make the best use of very limited tissue.''

Professor O'Toole can test for up to 250 mutations in one go, but within six months to a year new tests are expected to emerge that will make it possible to test for thousands.

Lisa Horvath, the head of medical oncology at Royal Prince Alfred, said the program was allowing her to stop ''napalming people with chemotherapy''.

Just five years ago everyone with non-small-cell lung cancer got the same treatment, but now she was able to modify the treatment in about 25 per cent of cases, Professor Horvath said.

A spokeswoman for the Department of Health and Ageing said the government was making changes to adapt to the rapid development of the technology.

''In recognition that many applications for genetic tests have similarities between them, a more flexible, ''fit-for-purpose'' process of assessing genetic tests, such as those partnered with particular medicines, are being developed to accommodate these co-dependent relationships,'' she said.